Rheostat



Patented May 7, 1935 UNITE-D STATES PATENT OFFICE Application Febmry 5, 1932, Serial No. 591,079

13Cllhna.

This invention relates to rheostats and refers more particularly to rheostats used in conjunction with radio apparatus.

It is the object of this invention to provide a rheostat wherein the adjustment of resistance may be effected smoothly and uniformly.

Another object of this invention is to provide a rheostat wherein the adjustment of resistance is effected by rolling a contactor upon a circular resistance. y

In this connection it is the further object ci' this invention to provide novel mechanism embodying a contactor in the form of an obtuse cone and an actuator including an acute cone in rolling engagement therewith to roll the contacter over thecontact surface of the resistance.

Another object of this invention is to provide mechanism for rolling the contactar upon the resistor in such a manner that slippage between the contactor and the surface of the resistance is prevented withk the above and other objects' in viewwhich will appear as the description proceeds, this invention resides in the'novel construction,

combination and arrangementof parts substantially as hereinafter described and more particularly defined by the appended claims, it being understood that such changes in the precise embodiment of the hereindisclosed invention may be made as come within the scope of the claims.

The accompanying drawing illustrates one complete Aexample .of the physical embodiment of the invention constructed according'to the bst/ mode so far devised for the practical application of the principles thereof, and in which:

Fig. 1 is a sectional side view of the rheo stat;

Fig. 2 is a sectional view on the line 2-2, Fig. l;

Fig. 3 is a sectional view on the line 3-4, Fig. 1; i

Fig. 4 is a sectional view on the line 4 4,

` Fig. 1; and

conical contacter. The axes of the acute cone- (cl. zel-ss) y shapedI roller and the conical contacter member interset so kthat the desired rolling engagement is effected between the obtuse conical contactor and the surface of the resistor and stationary contact and likewise between the acute coneshaped reller and the contacter upon adjustment of the actuator.

Referring now more particularly to the accom'- panying drawing, in which like numerals indicate like parts throughout the several views, the l0 numeral I designates the obtuse conical contactor which is substantially rigid and arranged to roll on a flat annular contact surface of the resistor 2. The obtuse conical forml of the contactor member enablesl it to lie closely to the l5 resistor in its entirety.

The resistor is ordinarily comminuted carbon or other suitable substance upon a paper or other suitable ring. It is carried by an insulating supporting base 20 3 which also mounts the stationary terminal contact I arranged within the resistor in alinement therewith and concentric thereto.

The obtuse conical contactor member is free to roll at its side in a circle upon the resistor and 25 the terminal contact and thereby connect the 4resistor' at its point of contact therewith to the terminal contact.

It is kept from radial displacement upon the resistor and the terminal contact .by a pintle l.

The pintle is fastened to the supporting base by a rivet which is formed upon its inner end. The terminal contact is split by circular slits to form it into resilient rings which yield to keep the terminal contact from interfering with the contact disk in making contact with the resistor and to facilitate continuous contact between the terminal contact and the contact disk.

The contact disk` is kept in contact with the resistor and the terminal contact `and rolled v thereon by an actuator in which a crank 6 is carried by an operating spindle 1 at its inner end and connected to the acute cone shaped driving roller 8 at its outer end.

The crank is formed by a resilient ring having as an integral part thereof an inner hub fastened to the spindle and it carries an insulating bearing block 9 which is attached by rivets to'depending lugs upon its resilient ring.

The driving roller has the bearing block ar- 50 ranged within its groove to keep it from radial displacement upon the resistor and the terminal contact, and it has within the groove an arbor Il which rotates in a bearing formed by a slot in the bearing block.

The crank presses the driving roller upon the contact disk by the action of its resilient ring, and thereby the contact disk is kept in firm engagement with the resistor and the terminal contact and the driving roller is given sufficient traction upon the contact disk to readily roll thereon.

The operating spindle is carried by a supporting sleeve I I and it has upon its outer end a removable knob I2 to turn it to operate the actuator.

The sleeve is screw-threaded to enable it to be attached to a support by which the rheostat as a whole is carried and it carries a stop I3 to arrest the movement of the crank at each end of the resistor.

When the actuator is operated, the driving roller is rolled upon the contact disk and revolved around the center thereof, and thereby the contact disk is rolled upon the resistor and the terminal contact to vary the resistance in the circuit in which the resistor is connected.

The resistor forms a contact ring which may have other resistance than that inherent in itself.

'Ihe supporting sleeve carries a casing Il by which is carried the supporting base.

The supporting base is retained in the casing upon a seat inside its rim by lugs formed upon the casing and bent inward.

It is removable from the casing apart from the actuator to enable ready access to the parts carried thereby and other parts associated therewith.

The casing has the supporting base positioned thereon by a lug I5 upon the casing entering a notch in the supporting base.

The supporting base/carries terminals upon its outside to connect the resistor and the terminal contact in the circuit in which resistance isto be varied.

The resistor is connected at each end by a conducting rivet to a terminal I6, and the terminal contact is connected by the rivet upon the pintle to a terminal I'I.

The rheostat which is set forth herein to explain and exemplify the invention is susceptible of various modifications which will embody the invention as defined by the hereinafter claims.

The invention which is described in the foregoing specication is hereby claimed as follows:

1. A rheostat comprising a resistor in the form of an interrupted ring, a terminal contact arranged within said resistor, a contact member having a conical contact portion mounted to roll in a circle upon said resistor and said terminal contact to electrically bridge the same, and an actuator having a driving roller rotated and revolved thereby upon said contact member to roll the same upon said resistor and terminal contact.

2. A rheostat comprising a substantially annular resistor, a terminal contact arranged adjacent said resistor but electrically spaced therefrom, a contact member having a conical-contact portion to roll in a circle upon said resistor and said terminal contact and electrically bridge the same, an actuator having a driving roller rotated and revolved thereby upon said contact member to roll the same upon said resistor and terminal contact, a base carrying said resistor and terminal contact, and terminals connected with said resistor and said terminal contact independently of the actuator.

3. A rheostat comprising a substantially annular stationary contact having a high electrical resistance, a terminal contact arranged adjacent said stationary contact, a contactor having a substantially conical contact portion arranged to roll upon said stationary contact and said terminal contact to electrically bridge the same, and an actuator having a driving roller rotated thereby upon said contactor to roll said contactor upon the stationary contact and the terminal contact.

4. A rheostat, comprising an insulating base, an annular resistor carried by said base and having a contact surface, a circular terminal contact arranged on said base concentric with said resistor and spaced therefrom, a movable contact member having the shape of a cone and arranged to roll upon said resistor contact surface and upon said terminal contact to connect them electrically, means to roll said contact member upon said resistor and said terminal contact, and terminals carried by said insulating base and connected to said annular resistor and to said terminal contact independently of said means.

5. A rheostat, comprising an annular resistor having a plane contact surface, a circular terminal contact member arranged within said resistor concentric therewith and spaced therefrom and provided with arcuate slits to increase its resilience, a movable contact member having the shape of a truncated obtuse cone and arranged to roll upon its side on the plane contact surface of said resistor and upon said resilient terminal contact, and means to roll said movable contact member and to press it upon said resistor and said resilient terminal contact to establish an electrical connection therebetween at any selected point upon said resistor.

6. A rheostat, comprising an annular resistor provided with a contact surface, a terminal contact member arranged within said resistor and spaced therefrom with its contact surface in the plane of the contact surface of said resistor, a movable contact member shaped to define the surface of a truncated obtuse cone and arranged to roll on its side upon said contact surfaces, and a driving roller having the shape of a truncated acute cone and arranged to roll in an orbit upon the inner surface of said movable contact member to roll it upon said contact surfaces to connect electrically any selected point lon said resistor to said terminal contact member.

7. A rheostat, comprising a flat annular contact, a resilient terminal contact arranged within said annular contact, and a conical movable contact arranged to roll upon its side on said fiat annular contact and upon said resilient terminal contact to engage said fiat contact throughout its Width and connect it electrically .to said terminal contact.

8. A rheostat, comprising an lannular resistor, a terminal contact spaced from said resistor and provided with arcuate slits to increase the resilience thereof, a movable conical contact member arranged to roll upon its side on said resistor and said terminal contact to establish electrical connection therebetween at any selected point on said resistor.

9. A rheostat, comprising a resistor, a terminal contact spaced from said resistor and provided 'with slots therein to increase the resilience thereof, and a movable contact member arranged to roll upon its side on said resistor and said terminal contact to establish contact between any selected point on said resistor and said terminal contact.

10. A rheostat comprising a resistor having a planar contact portion o! circular form, an obtuse conical member engageable with the contact portion of the resistor, a member rotatable about a xed axis intersecting the axis of the conical member and extending over the conical member, and an acute cone revoluble by the rotatable member and urged toward the conical member to roll thereon, whereby rotation'of the rotatable member produces a rotation of the acute cone and a rolling action between the acute cone and obtuse conical member and progresses the engagement of the conical member with the contact portion of the resistor.

11. A rheostat comprising a resistor having a planar contact portion oi circular form, an

obtuse conical member engageable with the con-l tact portion of the resistor, said conical `member being free to move in al1 directions in the plane of the resistor, a member rotatable about an axis intersecting the. axis of the conical member and extending over the conical member, and an acute cone revoluble by the rotatable member and urged toward the conical member vto roll thereon, whereby rotation of the rotatable member produces a rolling action between the acute conical member and obtuse cone and progresses the engagement of the conical member with the contact portion oi the resistor.

12. In a rheostat, a resistor having a substantially circular contact portion, a contact terminal having a substantially circular contact portion, means for mounting said resistor and said contact terminal in spaced relationship with one inside the other, a contact member having a conical contact portion arranged to roll simultaneously on the contacty portions of the. resistor and the contact terminal to electrically bridge the same, and actuating means for the contact` member to roll its conical contact portion along the contact portions of the resistor and contact terminal.

13. In a rheostat, a resistor having an unyielding contact portion, a terminal contact having a yielding contact portion in juxtaposition to the contact portion of the resistor but electrically spaced from the resistor, a conical contact member engaging the contact portions of said resistor and terminal contact to electrically bridge the same, and conical means to press the contact member'against the contact portions of the resistor and terminal contact and to `move said contact member to progress its points of engagement with the resistor and terminal contact along the contact portions thereof, the yieldability of the contact portion of the 

